Adam Clarke on John 5:19

The Son can do nothing of himself - Because of his inseparable union with the Father: nor can the Father do any thing of himself, because of his infinite unity with the Son.

What things soever he doeth, these also doeth the Son - God does nothing but what Christ does. What God does is the work of God, and proper to no creature - Jesus does whatsoever God does, and therefore is no created being. The Son can do nothing but what he sees the Father do: now, any intelligent creature may do what God cannot do: he may err - he may sin. If Jesus can do nothing but what God does, then he is no creature - he can neither sin nor err, nor act imperfectly. The conclusion from our Lord's argument is: If I have broken the Sabbath, so has God also; for I can do nothing but what I see him doing. He is ever governing and preserving; I am ever employed in saving.